1. Field of the Invention
The present invention relates generally to spindle motors and, more particularly, to a spindle motor which includes a stationary support shaft and a sleeve fitted over the stationary support shaft so as to be rotatable, and is constructed such that stable operating characteristics against external vibration can be ensured.
2. Description of the Related Art
Generally, in spindle motors, bearings which are provided around rotating shafts rotatably support the rotating shafts, thus ensuring a high level of operating characteristics. Because of these characteristics, the spindle motors are widely used as drive units of recording media, such as hard disk drives, magnetic disk drives, etc., which need high speed rotation.
Such a spindle motor uses a fluid dynamic bearing which is operated in such a way that a predetermined amount of fluid is injected between a rotating shaft and a sleeve, which coaxially supports the rotating shaft, so as to form dynamic pressure when the rotating shaft rotates, thus making the rotation of the rotating shaft smoother.
However, in the case where the rotating shaft is used in the spindle motor, when external impact is applied to the spindle motor, the amplitude of vibration of the rotating shaft and the rotor casing supported by the rotating shaft is excessively increased. To solve this problem, the use of a stationary support shaft in place of the rotating shaft is needed for the spindle motor.